1. Field of the Invention
The present invention relates to: an ultrasonic cleaning apparatus configured to clean an object to be processed, which is immersed in a cleaning liquid, with the use of ultrasonic waves; an ultrasonic cleaning method; and a storage medium storing a computer program for executing the ultrasonic cleaning method.
2. Description of Related Art
There has been conventionally known an ultrasonic cleaning apparatus configured to perform an ultrasonic cleaning (including a megasonic cleaning) of an object to be processed, such as a semiconductor wafer or a glass substrate for LCD, by using ultrasonic waves, with the object to be processed being immersed in a cleaning liquid such as a deionized water or a chemical liquid stored in a cleaning tank (see, JP2003-209086A, for example). In the ultrasonic cleaning apparatus, a vibrator capable of generating ultrasonic vibration is attached to a bottom part of the cleaning tank, and an ultrasonic oscillator that makes the vibrator ultrasonically vibrate is connected to the vibrator.
When an object to be processed is cleaned in such an ultrasonic cleaning apparatus, the vibrator is made to ultrasonically vibrate by the ultrasonic oscillator, with the object to be processed being immersed in the cleaning liquid in the cleaning tank. Thus, the ultrasonic vibration is propagated to the cleaning liquid, so that ultrasonic waves are radiated from below to the object to be processed. Therefore, particles adhering to the object to be processed are removed. In this manner, the object to be processed is ultrasonically cleaned.